Stress Distribution at Notch Tip

2006 ◽  
pp. 17-40
Keyword(s):  
Stress Distribution ◽  
Notch Tip

Notch tip stress distribution in strain hardening materials

1978 ◽  
Vol 14 (5) ◽  
pp. 501-508 ◽  
Author(s):  
R. C. Bates ◽  
A. T. Santhanam
Keyword(s):  
Stress Distribution ◽  
Strain Hardening ◽  
Notch Tip

Strength Evaluation of Notch Structure for Semiconductor Encapsulant Resin

2002 ◽  
Vol 124 (4) ◽  
pp. 323-327 ◽  
Author(s):  
Noriyasu Kawamura ◽  
Takashi Kawakami ◽  
Kikuo Kishimoto ◽  
Masaki Omiya ◽  
Toshikazu Shibuya
Keyword(s):  
Stress Distribution ◽  
Critical Stress ◽  
Epoxy Resins ◽  
Fracture Behavior ◽  
Stress Distributions ◽  
Strength Evaluation ◽  
Notched Specimens ◽  
Fracture Tests ◽  
Notch Tip ◽  
Semiconductor Encapsulant

Plastic encapsulated semiconductor packages may crack at the corner regions of die pads or chips if internal delamination occurs at an elevated temperature during the reflow soldering process. Thus, the structural strength design around the notch structures, which will be formed in the encapsulant resin due to the delamination, is considered one of the most important issues. Especially, it becomes a more critical item of the package development in order to realize the reflow process with lead-free solder materials, whose melting points are higher than that of Sn63-Pb37. In this study, the fracture behavior of notched specimens, which were made of silica particulate-filled epoxy resins and modeled as the corner regions in actual packages, were studied with experimental and numerical analyses. First, the fracture tests of the notch structure of semiconductor encapsulant resin were carried out. A notch tip with several different radii was introduced to the specimen. The specimens were fractured by a three-point bending load. Second, the strength evaluation of the notch structure was carried out. The critical stress distribution σCr=max.[KIC/2πr1/2,σB] was used to determine the crack initiation at the notch tip. It is assumed that a fracture occurs when, at any point near the notch tip, the stress distribution exceeds the critical stress distribution determined by fracture toughness and bending strength. Three-dimensional finite element analysis was carried out to obtain the stress distributions around the notch tip in the specimen. The calculated stress distributions around the notch tip were compared with the critical stress distribution to estimate the fracture load of the specimen. Estimated fracture loads at room temperature and at high temperature were compared with the results of the fracture tests. It was confirmed that the predicted results based on the critical stress distribution corresponded very well with the experimental results. The validity of the criterion was confirmed by studying the fracture behavior of the notched specimens of actual silica particulate filled epoxy resins.

A Method for Determining the Elastic-Plastic Response Ahead of a Notch Tip

1999 ◽  
Vol 121 (3) ◽  
pp. 313-320 ◽  
Author(s):  
C. H. Wang ◽  
W. Guo ◽  
L. R. F. Rose
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Analytical Method ◽  
Strain Distribution ◽  
Driving Force ◽  
Notch Root ◽  
Close Correlation ◽  
Plastic Response ◽  
Elastic Plastic ◽  
Notch Tip

The stress distribution ahead of a notch tip is the prerequisite to calculating the driving force for cracks emanating from notches. This article first examines whether two commonly used engineering methods, which are often employed to determine the response at a notch tip, can be applied to evaluate the elastic-plastic response ahead of a notch tip. It is found that both methods would significantly underestimate the stress-strain distribution ahead of a notch tip. Based deformation theories of plasticity, and analytical method is then developed, taking into account of the effects of stress redistribution induced by notch plasticity and the in-plane and through-thickness constraints near the notch root. Predictions are shown to be in close correlation with finite element results.

The concerted use of SEM, TEM, and SCM for examination of resin-dentin interfaces

1994 ◽  
Vol 52 ◽  
pp. 476-477
Author(s):  
B. Van Meerbeek ◽  
L. J. Conn ◽  
E. S. Duke
Keyword(s):  
Surface Layer ◽  
Stress Distribution ◽  
Phosphoric Acid ◽  
Bonding Mechanism ◽  
Restorative Dentistry ◽  
Dental Adhesive ◽  
Low Viscosity ◽  
Dentin Adhesives ◽  
Acid Etch ◽  
Tooth Tissue

Restoration of decayed teeth with tooth-colored materials that can be bonded to tooth tissue has been a highly desirable property in restorative dentistry for many years. Advantages of such an adhesive restorative technique over conventional techniques using non-adhesive metal-based restoratives include improved restoration retention with minimal sacrifice of sound tooth tissue for retention purposes, superior adaptation and sealing of the restoration margins in prevention of caries recurrence, improved stress distribution across the tooth-restoration interface throughout the whole tooth, and even reinforcement of weakened tooth structures. The dental adhesive technology is rapidly changing. An efficient resin bond to enamel has already long been achieved. Its bonding mechanism has been fully elucidated and has proven to be a durable and reliable clinical treatment. However, bonding to dentin represents a greater challenge. After the failures of a dentin acid-etch technique in imitation of the enamel phosphoric-acid-etch technique and a bonding procedure based on chemical adhesion, modern dentin adhesives are currently believed to bond to dentin by a micromechanical hybridization process. This process is developed by an initial demineralization of the dentin surface layer with acid etchants exposing a collagen fibril arrangement with interfibrillar microporosities that subsequently become impregnated by low-viscosity monomers. Although the development of such a hybridization process has well been documented in the literature, questions remain with respect to parameters of-primary importance to adhesive efficacy.

Residual stress distribution in laser alloying zone with FeCSiB powder

2008 ◽  
Author(s):  
Zhengyang Li ◽  
Haiyan Zhao ◽  
Minlin Zhong ◽  
Bin Zhang ◽  
Yu Gu ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stress Distribution ◽  
Laser Alloying
Sign in / Sign up

Export Citation Format

Share Document